JP2012015600A - Mobile communication system, communication method, base station and server - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain transmission of appropriate service data if an available communication rate is lower than a service rate due to handover.SOLUTION: A radio communication system 1 comprises a base station 100 which can communicate with a mobile terminal 300, and a server 200 which is provided in a position higher than the base station. The base station comprises notification means 111 which notifies the server of a communication rate available at the base station. The server comprises marking means 214 which marks prescribed data in service data depending on difference between a service rate of the service data to be transmitted to the mobile terminal and the notified communication rate. The base station transmits the service data transmitted by the server to the mobile terminal depending on whether or not the service data has a mark.

Description

  The present invention relates to a technical field of a mobile communication system, a communication method, a base station, and a server that enable a user terminal to be handed over in different mobile communication systems.

  Along with the increase in the volume of content to be used, a new generation mobile communication system in which the communication rate of data transmission / reception is improved so as to enable high-speed data communication has been studied and put into practical use. On the other hand, there is a certain demand for an old-type mobile communication system having a relatively low communication rate simultaneously with the latest mobile communication system. For this reason, a situation where a plurality of different mobile communication systems operate in the future can be considered.

  In such a situation where various types of mobile communication systems are mixed, it is required to provide a stable service between different mobile communication systems so as not to make the user aware of the mobile communication system being used. It is done. For example, when a user terminal is handed over between mobile communication systems, it is important that stable service can be continued.

  Specifically, when a user terminal is handed over from a mobile communication system with a relatively high communication rate to a mobile communication system with a relatively low communication rate, large-capacity data that is expected to be used at a high communication rate, etc. May not be usable in a mobile communication system after handover.

  A technique that enables sufficient data to be communicated to a user even during a handover between mobile communication systems having different communication rates has been studied. For example, the following prior art documents describe a technique for guaranteeing QoS (Quality of Service) at the time of handover to a base station having a different communication rate.

Special table 2009-537089 JP 2005-328441 A JP 2004-312062 A

  As described above, when the communication rate varies greatly between different mobile communication systems, if a user terminal is handed over from a mobile communication system with a high communication rate to a mobile communication system with a low communication rate, the communication rate is insufficient and the service is used. It may not be possible.

  For such technical problems, service data is provided so that it can be used even in mobile communication systems with relatively low communication rates, for example, by changing the encoding method of large-capacity data such as moving images. A countermeasure for reducing the service rate, which is the transmission rate at the time of transmission, can be considered. By reducing the service rate in this way, it is possible to continue using the service even after handover to a mobile communication system having a relatively low communication rate. On the other hand, there is a limit to the reduction of the service rate by the encoding method, and if the service rate after changing the encoding method is still higher than the communication rate, the use of the service cannot be continued as described above.

  In addition, even in the case of a 3.9G mobile communication system that is shared and used by user terminals accommodating a single radio resource, it can be used before and after the handover even within the same mobile communication system. Radio resources may change. For this reason, even if the handover does not straddle the mobile communication system, there is a possibility that the service use cannot be continued as described above.

  In addition, not only when the handover is performed but also when the communication rate fluctuates due to some factor, depending on the service rate, there is a possibility that the service use cannot be continued as described above.

  The present invention has been made in view of the above-described problems. A mobile communication system, a communication method, a base station, and a mobile communication system that enable continuation of service even when the communication rate fluctuates (for example, when the communication rate significantly decreases). It is an object to provide a server.

  In order to solve the above-described problem, the disclosed mobile communication system includes a base station that can communicate with a mobile terminal, and a server that is provided above the base station. For example, when starting communication with a mobile terminal, the base station includes a notification unit that notifies a server of a communication rate that can be used in the base station. The server includes marking means for marking predetermined data in service data transmitted to the mobile terminal. When the service rate, which is a transmission rate at the time of transmitting service data, exceeds the communication rate notified from the base station, the marking means is a predetermined unit in the service data according to the difference between the service rate and the communication rate. Mark the data. Further, the base station transmits, for example, the marked data among the service data transmitted from the server to the mobile terminal after starting communication with the mobile terminal.

  The disclosed communication method includes a notification step, a marking step, and a transmission step. In the notification step, an operation similar to the operation performed by the notification means described above is performed. In the marking process, an operation similar to the operation performed by the marking means described above is performed. In the transmission step, similar to the operation performed by the base station described above, an operation of transmitting the marked data among the service data to the mobile terminal is performed.

  The disclosed base station is a base station that transmits service data received from a server to a mobile terminal, and is marked in the service data in the same manner as the notification means described above and the operation performed by the above base station. Transmitting means for transmitting the received data to the mobile terminal.

  The disclosed server is a server that transmits service data to a mobile terminal via a subordinate base station in a mobile communication system, and includes the marking means described above.

  According to the above-described configuration, relatively important data can be selected and transmitted to the mobile terminal for providing a service to the user's mobile terminal. On the other hand, it is possible to select not transmitting data having relatively low importance to the mobile terminal. For this reason, it can suppress pressing down the communication rate in the mobile communication system after a hand-over.

  For this reason, the service can be continued even when the communication rate that can be used is significantly reduced by the handover.

It is a figure which shows the whole structure of a mobile communication system. It is a table | surface which shows the classification of a communication system, and a typical communication rate. It is a figure which shows the aspect of transmission of the service data according to a communication rate. It is a figure which shows the aspect of transmission in the case of changing the service rate of service data according to a communication rate. It is a figure which shows the aspect of transmission of the service data in case a radio | wireless resource is shared by multiple users. It is a block diagram which shows the structure and function of a base station. It is a block diagram which shows the structure and function of a data server. It is a sequence diagram which shows the flow of the hand-over process in a mobile communication system. 5 is a flowchart showing a flow of operations of a handover source base station during a handover process. 5 is a flowchart showing a flow of operations of a handover destination base station during a handover process. It is a flowchart which shows the flow of operation | movement of the data server at the time of a handover process. It is a flowchart which shows the flow of operation | movement of the base station at the time of the service data transmission according to marking. It is a sequence diagram which shows the flow of operation | movement at the time of the marking addition stop in a handover process. It is a sequence diagram which shows the flow of the hand-over process in a mobile communication system. It is a figure which shows the aspect of the marking added with respect to service data. It is a figure which shows the aspect of marking addition and service data transmission. It is a flowchart which shows the flow of operation | movement of the data server which concerns on marking addition. It is a flowchart which shows the flow of operation | movement of the data server which concerns on marking addition. It is a flowchart which shows the flow of operation | movement of the data server which concerns on marking addition.

  Embodiments for carrying out the invention will be described below.

(1) Network With reference to FIG. 1, a basic configuration of a mobile communication system 1 which is a specific example of the disclosed mobile communication system is shown. As shown in FIG. 1, the mobile communication system 1 has a configuration in which a plurality of base stations 100a to 100f are connected to a data server 200 via a core network. The base stations 100a to 100f form a cell that is a radio section under their control, and communicate with a mobile terminal (UE: User Equipment) 300 located in the cell. For example, in the example illustrated in FIG. 1, the UE 300 is located in the cell of the base station 100a, and receives service data transmitted from the data server 200 on the core network via the base station 100a. When the base stations 100a to 100f are described without distinction, in the mobile communication system 1 described using the notation of the base station 100, the base stations 100a to 100f are used for communication of different data. A communication method may be adopted. In the example of FIG. 1, it is assumed that the base stations 100a to 100c employ one communication method, and the base stations 100d to 100f employ another communication method. Examples of communication systems include 2G (second generation) GSM (Global System for Mobile communications), LTE (Long Term Evolution) called 3.9G, and the like.

  In different communication schemes, for example, the protocol for data transmission / reception is different, so the communication rate at the time of data transfer is different. Typically, in response to a request for large-capacity data communication, the communication rate tends to be greatly improved every time the generation of the communication method is changed.

  With reference to FIG. 2, main communication methods and typical communication rates in the communication methods will be described. In 2G GSM, the communication rate is 171.2 Kbps (bit per second). In 3G W-CDMA (Wideband Code Division Multiple Access), the communication rate is 384 Kbps. In 3.5 G HSDPA (High Speed Downlink Packet Access), the communication rate is 14 Mbps. In 3.9G LTE, the communication rate is 300 Mbps. In 4G, the communication rate is 1 Gbps.

  In a communication method with a high communication rate, a higher service rate for transmitting service data can be ensured according to the communication rate. For example, as shown in FIG. 3 (a), when the communication method adopted in the radio section between the base station 100 and the UE 300 is of a relatively high communication rate, the comparison is made within the range of the communication rate. Service data can be transmitted at a high service rate. For this reason, since it becomes possible to transmit a lot of service data at once, a large amount of data such as a moving image can be suitably transmitted. On the other hand, as shown in FIG. 3 (b), when the communication scheme adopted in the radio section between the base station 100 and the UE 300 is of a relatively low communication rate, it is within the range of the communication rate. Service data can only be transmitted at a relatively low service rate. For this reason, since the service data that can be transmitted at a time is smaller, it is not suitable for transmission of large-capacity data such as moving images.

  In the mobile communication system 1 in which a base station 100 that employs a different communication scheme exists, when a UE 300 handover occurs between the base stations 100 that employ a different communication scheme, the available communication rate changes significantly before and after the handover. There is a case. For example, in the example of FIG. 1, there may be a case where different communication schemes are employed between the base stations 100a to 100c and the base stations 100d to 100f.

  For example, when a handover is performed from a base station 100 that employs W-CDMA to a base station 100 that employs LTE, the communication rate is approximately 1000 times, and service data can be transmitted favorably.

  On the other hand, when handover is performed from the LTE base station 100 to the W-CDMA base station 100, the communication rate is approximately 1/1000, which may hinder suitable transmission of service data. In particular, when the service data transmitted from the data server 200 to the UE 300 at the time of handover is large-capacity data such as a moving image, the service rate required for transmitting the service data exceeds the available communication rate, Service data may not be transmitted properly. FIG. 3C is a diagram illustrating a communication state after the UE 300 has handed over from the LTE base station 100 to the W-CDMA base station 100. In the W-CDMA base station 100, since the service rate required for transmitting the service data currently being transmitted to the UE 300 exceeds the communication rate, the transmission of service data is hindered. In this case, in the W-CDMA base station 100, service data that cannot be transmitted is discarded, and only service data in a range that can be transmitted at the communication rate is transmitted to the UE 300. For this reason, if it is a moving image, there exists a technical problem that a defect | deletion arises in data, such as becoming fragmented reproduction.

  A method for dealing with such a technical problem by changing the service rate can be considered. For example, when the service data is encoded data such as a moving image, a method of changing the encoding method to a service rate that can be accommodated in a communication rate that can be used in the base station 100 after handover can be considered. With reference to FIG. 4, a communication situation when the above-described method is employed will be described. When the UE 300 is communicating with the base station 100 having a relatively high communication rate (FIG. 4 (a)) and handing over to the base station 100 having a relatively low communication rate, the base having a relatively low communication rate. The service data encoding method is changed according to the communication rate available at the station 100 (FIG. 4B). As a result, the service rate of the service data is reduced, and the service data can be transmitted even when the communication rate is lower than the original service rate due to handover between the base stations 100 having different communication methods. However, there is a limit to the change rate of the service rate due to the change of the encoding method and the like, and the available communication rate is extremely lowered like a handover from the 4G base station 100 to the 2G base station 100. In some cases, it may not always be possible.

  On the other hand, even in the handover between base stations 100 that adopt the same communication method, the communication rate may change greatly before and after the handover, which may cause the above-described technical problem. For example, in the LTE base station 100, when there are a plurality of accommodated UEs 300, a method in which a plurality of UEs 300 are shared and used by the plurality of UEs 300 is employed (FIG. 5A). Therefore, the communication rate that can be used by a single UE 300 varies depending on the number of UEs 300 accommodated in the base station 100. Therefore, when the UE 300 is handed over from the LTE base station 100 to another LTE base station 100, the number of UEs accommodated in the handover destination base station 100 is the number of UEs accommodated in the handover source base station 100. When larger, the communication rate which UE300 can use falls. As a result, the communication rate available in the handover destination base station 100 is lower than the service rate required for transmitting the service data currently being transmitted to the UE 300, so that the transmission of service data is hindered. .

(2) Configuration Example Hereinafter, the configuration of an apparatus for implementing the present invention and the operation of each unit will be described. First, configuration examples of the base station 100 and the data server 200 included in the mobile communication system 1 will be described with reference to FIGS. 6 and 7.

  FIG. 6 is a block diagram illustrating a hardware configuration of the base station 100 and functional units for communication control in each unit. Note that each function unit described below is shown by dividing the functions of each unit for the sake of convenience, and is not limited to a mode in which each function unit actually exists as an independent entity. Alternatively, it may be a function in software.

  The base station 100 includes a CPU 101, a memory 102, a bus switch 103, a DSP (Digital Signal Processor) 104, an exchange side interface chip 105, a radio side interface chip 106, and a buffer memory 107. .

  The CPU 101 is a control unit that controls the operation of the entire base station 100, and is connected to the DSP 104 via the bus switch 103, and transmits and receives signals for operation control. In addition, the CPU 101 includes a call control unit 111 that is a functional unit that controls call processing in the base station 100, and controls the operation of each unit in accordance with the connection status with the UE 300.

  The call control unit 111 of the embodiment further secures resources when the UE 300 is handed over to the base station 100, and calculates an available communication rate that is determined according to the resources. The call control unit 111 transmits the calculated communication rate to the base station 100 that is the handover source of the UE 300 via the interface chip 105. Further, the call control unit 111 receives the communication rate transmitted as described above and transmits it to the data server 200 when the UE 300 in the subordinate region hands over to another base station 100.

  The memory 102 is a memory for storing data, and stores, for example, a program for operating the CPU 101. The CPU 101 controls each unit by reading the program.

  The DSP 104 performs signal processing for processing data transmitted from the data server 200 via the core network and converting the data into data to be transmitted to the UE 300. For this reason, the DSP 104 has an exchange-side protocol termination unit 112 that terminates a signal from the core network, and a radio-side protocol termination unit 114 that converts data received from the exchange-side protocol termination unit 112 into a wireless protocol. . Further, the DSP 104 includes a marking processing unit 113 that detects marking in service data transmitted from the data server 200 and selectively transmits data to the UE 300.

  The exchange-side interface chip 105 is a chip having an interface function for communicating with an upper node on the core network such as the data server 200 or another base station 100. Specifically, data transmission / reception is performed by the operation of the exchange-side interface 115 which is one functional unit in the exchange-side interface chip 105.

  The radio-side interface chip 106 is a chip having an interface function for performing communication with the UE 300 located in the cell under its control. Specifically, the operation of the wireless side interface 116, which is one functional unit in the wireless side interface chip 106, forms cells under the control of the antenna via a not-shown antenna, and transmits and receives data.

  The buffer memory 107 is a buffer memory that temporarily stores data processed by the DSP 104. The buffer memory 107 includes, for example, a network buffer 117 that temporarily stores service data received from the core network, and a radio-side buffer 118 that temporarily stores data to be transmitted to the UE 300.

  FIG. 7 is a block diagram illustrating a hardware configuration of the data server 200 and functional units for communication control in each unit. Note that each function unit described below is shown by dividing the functions of each unit for the sake of convenience, and is not limited to a mode in which each function unit actually exists as an independent entity. Alternatively, it may be a function in software.

  The data server 200 includes a CPU 201, a memory 202, a bus switch 203, a DSP 204, a hard disk 205, an interface chip 106, and a buffer memory 206.

  The CPU 201 is a control unit that controls the overall operation of the data server 200, and is connected to the DSP 204 via the bus switch 203, and transmits and receives signals for operation control. In addition, the CPU 201 includes a call control unit 211 that is a functional unit that controls call processing in the data server 200.

  The call control unit 211 controls the operation of each unit to transmit service data according to the connection status of the UE 300 to the subordinate base station 100. Further, the call control unit 211 compares the communication rate notified from the base station 100 and usable in the base station 100 that is the handover destination of the UE 300 with the service rate of the service data provided to the UE 300, Judgment is made as to whether or not marking should be added to the service data. Based on the determination result, the call control unit 211 transmits an instruction related to marking to the marking adding unit 214.

  The memory 202 is a memory for storing data, and stores, for example, a program for operating the CPU 201. The CPU 201 controls each unit by reading the program.

  In response to a transmission request from the UE 300, the DSP 204 generates service data for transmission from the content file read from the hard disk 205, and transmits it to the base station 100 via the core network. Therefore, the DSP 204 includes a service data generation unit 212 that generates service data from the content file read from the hard disk 205, and an exchange that assigns an exchange-side protocol for transmitting the generated service data via the core network. Side protocol generation unit 213. Further, the DSP 204 performs marking on the service data in response to an instruction from the call control unit 211, such as when the communication rate at the handover destination base station 100 is lower than the service rate of the service data to be transmitted. Is provided.

  The hard disk 205 has a data storage 215 that stores content files provided by the data server. The data storage 215 reads and transmits a desired content file in response to a request from the UE 300.

  The interface chip 206 is a chip having an interface function for performing communication with the base station 100 via the core network. Specifically, data transmission / reception is performed by the operation of the exchange-side interface 216 which is one functional unit in the interface chip 205.

  The buffer memory 207 is a buffer memory that temporarily stores data processed by the DSP 204. The buffer memory 207 includes a network buffer 217 that temporarily stores the content file read from the data storage 215 for transmission.

(3) Operation Example With reference to FIGS. 8 to 12, the operation of the mobile communication system 1 will be described. FIG. 8 is a sequence diagram showing a process flow at the time of handover of the UE 300 in the mobile communication system 1. FIG. 9 is a flowchart showing a flow of processing in the base station 100a as a handover source. 10 and 12 are flowcharts showing the flow of processing in the base station 100b that is the handover destination. FIG. 11 is a flowchart showing the flow of processing in the data server 200.

  As shown in FIG. 8, before the handover of the UE 300, the UE 300 is accommodated in the base station 100a. The data server 200 transmits service data for the UE 300 to the base station 100a, and the base station 100a transmits the received service data to the UE 300 at a predetermined service rate.

  When the communication quality of the UE 300 with the base station 100a deteriorates, the UE 300 reports the deterioration of the communication quality to the base station 100a. Upon receiving the report, the call control unit 111 of the base station 100a determines whether to perform a handover (HO: Hand Over) of the UE 300 to the base station 100b. Thereafter, the base station 100a transmits a handover request (HO request) message to the base station 100b.

  The call control unit 111 of the base station 100b that has received the handover request message secures radio resources to be allocated to the UE 300 after the handover. Further, a communication rate that can be used by the UE 300 is calculated according to the reserved radio resource. Thereafter, the base station 100b transmits a handover response (HO response) message and a communication rate available after the handover to the base station 100a.

  The base station 100a that has received the handover response message transmits a communication destination change request message of the UE 300 and a communication rate that can be used in the handover destination base station 100b to the data server 200.

  The call control unit 211 of the data server 200 that has received the communication destination change request message performs processing to change the transmission destination of service data for the UE 300 from the base station 100a to the base station 100b. In addition, the call control unit 211 compares the notified communication rate available in the base station 100b with the service rate required for service data transmission. The call control unit 211 determines whether to mark the data in the service data based on the comparison result, and instructs the marking adding unit 214 whether marking is necessary. If the communication rate available in the base station 100b is lower than the service rate, the marking adding unit 214 marks predetermined data in the service data based on an instruction from the call control unit 211. At this time, for example, marking is added to the data portion of the service data that exceeds the communication rate available at the base station 100b. Thereafter, the data server 200 transmits the service data with the marking added to the base station 100b.

  On the other hand, in parallel with the communication destination change process by the data server 200, the base station 100a transmits a handover instruction (HO instruction) message to the UE 300 to instruct execution of the handover to the base station 100b. The UE 300 that has received the handover instruction message performs handover to the base station 100b and transmits a handover notification (HO notification) message to the base station 100a.

  After performing the handover, the marking processing unit 113 of the base station 100b that has received the service data transmits to the UE 300 the data to which the marking is added from the received service data. On the other hand, the marking processing unit 113 performs processing for discarding data to which no marking is added. Thereafter, the base station 100b transmits service data to the UE 300.

  The flow of operations of the handover source base station 100a in the above-described handover process will be described together with the flowchart of FIG.

  The call control unit 111 of the base station 100a receives a report of communication quality degradation from the UE 300 (step S101), and determines whether or not the handover to the base station 100b with high communication quality in the UE 300 is necessary (step S102).

  When it is determined that a handover to the base station 100b is to be performed (step S102: Yes), the base station 100a transmits a handover request message to the handover destination base station 100b (step S103). As a response to the handover request message, the base station 100a receives a handover response message (step S104) and a communication rate available after the handover from the base station 100b (step S105).

  Subsequently, the base station 100a transmits a communication destination change request message of the UE 300 and a communication rate that can be used in the handover destination base station 100b to the data server 200 (step S106). As a response to the communication destination change request message, the base station 100a receives the communication destination change response message from the data server 200 (step S107).

  Receiving the communication destination change response message, the base station 100a transmits a handover instruction message to the UE 300, and instructs execution of the handover to the base station 100b (step S108). As a response to the handover instruction message, the base station 100a receives a handover notification message for notifying the completion of the handover process for the base station 100b from the UE 300 (step S109). Thereafter, the base station 100a releases radio resources reserved for call processing for the handed over UE 300 (step S110), and ends the processing.

  The flow of operations of the handover destination base station 100b in the above-described handover process will be described together with the flowchart of FIG.

  After receiving the handover request message from the handover source base station 100a (step S201), the call control unit 111 of the base station 100b secures radio resources to be allocated to the UE 300 after the handover (step S202).

  Next, the call control unit 111 of the base station 100b calculates a communication rate that can be used by the UE 300 after the handover based on the secured radio resource (step S203). Thereafter, as a response to the handover request message, the base station 100b transmits a handover response message (step S204) and a communication rate that can be used after the handover to the base station 100a (step S205).

  The operation flow of the data server 200 in the above-described processing at the time of handover will be described together in the flowchart of FIG.

  Before the handover process is performed, the data server 200 transmits service data for the UE 300 to the base station 100a that accommodates the UE 300 (step S301). Thereafter, the call control unit 211 of the data server 200, together with the communication destination change request message (step S302) for changing the communication destination of the UE 300 related to the handover process from the handover source base station 100a to the base station 100b, the handover destination base station The communication rate available in 100b is notified (step S303).

  Subsequently, the call control unit 211 of the data server 200 acquires the service rate of the service data currently being transmitted to the UE 300 (step S304). Then, the call control unit 211 of the data server 200 compares the acquired service rate with the communication rate that can be used in the handover destination base station 100b (step S305).

  When the current service rate is equal to or lower than the communication rate that can be used in the handover destination base station 100b (step S305: No), the call control unit 211 of the data server 200 does not perform the marking addition process. The setting is made as follows (step S306).

  On the other hand, when the current service rate exceeds the communication rate available at the handover destination base station 100b (step S305: Yes), the call control unit 211 of the data server 200 transmits the service data in the service data to the marking adding unit 214. The marking adding process for adding the marking to the predetermined data is performed (step S307). A specific marking process operation will be described in detail later.

  At the same time as or after the setting of marking addition, the call control unit 211 of the data server 200 performs a process of changing the transmission destination of the service data to the handover destination base station 100b in response to the communication destination change request (Step S1). S308). After the processing, the data server 200 transmits a communication destination change response message indicating that the communication destination change processing has been completed to the base station 100a (step S309).

  Thereafter, the data server 200 transmits service data for the UE 300 to the base station 100b that newly accommodates the UE 300 (step S310). When marking is added to the service data by the marking adding unit 214 described above, data indicating marking is added to the packet header or protocol header in the service data, for example, along with data indicating that the marking is added. Added.

  The operation flow of the base station 100b in the process during communication of service data after the handover will be described together with the flowchart of FIG.

  After the handover, the base station 100b receives service data for the UE 300 from the data server 200 via the exchange in the core network (step S401). Specifically, one packet of service data divided into a plurality of packets for transmission is received.

  The exchange-side protocol termination unit 112 of the base station 100b terminates the exchange-side protocol in the received packet (step S402). At this time, the marking processing unit 113 that has received the packet from the exchange-side protocol termination unit 112 checks whether or not data indicating marking addition is added to the transmitted packet (step S403).

  When the presence of data indicating marking is confirmed (step S403: Yes), the marking processing unit 113 investigates whether marking is added to the packet (step S404).

  When marking is added to the investigated packet (step S404: Yes), the marking processing unit 113 passes the packet to the UE 300 so that the packet is transmitted to the UE 300. The wireless-side protocol termination unit 114 converts the transferred packet into a wireless-side protocol and passes it to the wireless-side interface 116 (step S405). Then, the radio side interface 116 transmits the passed packet to the UE 300 (step S406).

  On the other hand, when marking is not added to the investigated packet (step S404: No), the marking processing unit 113 checks whether or not there is a free capacity in the wireless buffer 118 (step S407). If there is free space (step S407: No), the marking processing unit 113 temporarily stores the packet without marking in the wireless side buffer 118. The wireless-side protocol termination unit 114 converts the packet without the marking stored in the buffer into the wireless-side protocol in the same manner as the packet with the marking described above, and passes it to the wireless-side interface 116 (step) S405).

  When there is no free space in the wireless side buffer 118 (step S407: Yes), the marking processing unit 113 discards a packet to which no marking is added (step S408).

  When the service data rate does not exceed the communication rate that can be used after handover at the time of handover between the mobile communication system and the cell, the data server 200 stops adding marking to the service data. The sequence of operations at this time is shown in the sequence diagram of FIG. In the example of FIG. 13, since the communication rate after handover is equal to or higher than the service rate, it is not necessary to perform selective data thinning by adding marking, and the original service data passes through the base station 100b. It is transmitted to UE300.

  Further, the handover destination base station 100b may notify the data server 200 of the communication rate directly instead of notifying the base station 100a of the available communication rate together with the handover response message. The sequence of operations at this time is shown in the sequence diagram of FIG.

(4) Marking Processing Example With reference to FIG. 15 to FIG. 19, an aspect of marking addition to service data by the marking adding unit 214 of the data server 200 will be described. FIG. 15 is a diagram illustrating an example of an additional position of marking data in an IP packet for transmission of service data. FIG. 16 is an image showing how marking is added to data in service data. FIGS. 17 to 19 are flowcharts showing examples of the flow of operations performed by the marking adding unit 214 when marking is added.

  With reference to FIG. 15, the marking addition position for the service data will be described. There are two types of data relating to marking. One is data indicating the presence or absence of marking in the service data. The data is added to the header portion of the service data packet (for example, “Marking Bit” in FIG. 15). The other data is data indicating actual marking itself, and the data is added by marking the service data. The data is typically added to a protocol header on the switch side that is terminated at the switch side protocol termination unit 112 of the base station 100b. More specifically, for example, the data may be added to an empty area in the protocol header on the exchange side, such as “Extension Header” in FIG. 15, or an empty area generated by extending the protocol header area. Good.

  The data indicating the presence / absence of marking and the data indicating the marking itself may each be added to other parts. However, since the service data itself generated in the data server 200 is not terminated in the base station 100b, it is not preferable to add data to the service data. It is preferable that the data related to the marking is stored in the protocol header on the exchange side which is terminated in the base station 100b and is added to the service data. Further, the marking adding unit 214 may add marking ON data as data indicating the marking itself, and may add marking OFF data for a packet to which no marking is added.

  With reference to FIG. 16, a description will be given of how marking is added to service data by the marking adding unit 214 of the data server 200.

  The marking adding unit 214 of the data server 200 adds marking according to the ratio at which the service rate calculated by the call control unit 211 exceeds the communication rate. For example, when the ratio between the service rate and the communication rate is N: M (N> M), the marking adding unit 214 adds marking to M data out of the N service data, and the remaining NM Marking is not added to individual data.

  The marking adding unit 214 may add markings at equal intervals among the N pieces of service data. In this case, for example, as shown in FIG. 16 (a), when N: M is set to 2: 1 for service data from 1 to 6, for service data of 1, 3 and 5 Marking is added. When setting in this way, the service data 1, 3 and 5 selected at equal intervals among the original service data 1 to 6 generated in the data server 200 reach the UE 300. For this reason, for example, in the case of service data generated from a content file such as a moving image, frames are transmitted to the UE 300 at a predetermined interval. For this reason, the service rate of service data can be reduced without significantly affecting the use of service data by the user.

  Further, as shown in FIG. 16 (b), the marking adding unit 214 performs burst processing on service data determined by a rate ratio, such as 1 to 3 for service data 1 to 6. Marking may be added to. In the case of setting in this way, for example, by marking the data with relatively high importance in the service data in a burst manner, the data with high importance is transmitted to the UE 300 while reducing the service rate. Can be delivered.

  In addition, as shown in FIG. 16C, the marking adding unit 214 adds markings to service data randomly determined, such as 1, 2 and 5, for service data 1 to 6 May be.

  The operation flow of the marking adding unit 214 in the marking adding process will be described together with the flowchart of FIG.

  The marking adding unit 214 receives the service data divided into packets by the exchange-side protocol generation unit 213 (step S501). Subsequently, the marking adding unit 214 internally generates a pseudo random number A of 0 or 1 (step S502).

  Subsequently, the marking adding unit 214 compares the generated pseudorandom number A with the ratio of the communication rate to the service rate (step S503). At this time, since the ratio of the communication rate to the service rate is 1 or less, when the generated pseudorandom number A is 0, the pseudorandom number A is smaller, and when the generated pseudorandom number A is 1, the pseudorandom number A is larger. When the pseudo random number A is smaller than the ratio of the communication rate to the service rate (step S503: Yes), the marking adding unit 214 adds data indicating the presence / absence of marking to the packet header (step S504), and marks the protocol header with the marking. It adds (step S505). When the pseudo random number A is larger than the ratio of the communication rate to the service rate (step S503: No), the marking adding unit 214 adds data indicating the presence / absence of marking to the packet header (step S506), while in the protocol header. No marking is added (step S507).

  Thereafter, the marking adding unit 214 transmits the packet to the base station 100b via the exchange side interface 216 (step S508). The above operation is repeatedly executed until the transmission of service data is completed (step S509: Yes).

  The data server 200 may determine whether or not marking is added according to the type of service data. An example of the operation of the marking adding unit 214 in this aspect will be described with reference to the flowchart of FIG.

  In this aspect, the marking adding unit 214 performs the marking adding process shown in the flowchart of FIG. 17 when the service data is data having real-time characteristics such as moving images and music that are continuous in time series (step S601: Yes). Implement (step S602). On the other hand, with respect to data that does not have real-time properties, it is set not to perform marking addition processing (step S603).

  According to this aspect, the marking adding unit 214 adds marking for data having real-time characteristics in order to prevent a delay due to the service rate exceeding the communication rate. The specific mode of marking added to each service data may be the same as that shown in FIG. On the other hand, the call control unit 211 does not perform marking addition setting by the marking adding unit 214 for data that does not have strict real-time properties, such as mail. For this reason, it is prevented that service data is thinned out due to the addition of marking, and priority is given to the arrival of the original service data at the UE 300.

  The data server 200 may determine whether or not a marking is added based on information in the content file stored in the data storage 215. An example of the operation of the marking adding unit 214 in this aspect will be described with reference to the flowchart of FIG.

  First, the service data generation unit 212 reads out data for one frame from the content file transmitted to the UE 300 (step S701). Next, the service data generation unit 212 determines whether or not information serving as a flag for performing marking addition exists in the data of the frame (step S702). If the marking flag exists (step S702: Yes), the service data generation unit 212 sets the marking addition flag to ON (step S703). If there is no marking flag (step S702: No), the marking addition flag is set to OFF (step S704).

  The exchange-side protocol generation unit 213 to which the frame data has been transferred divides the data and generates a packet for transmission (step S705).

  If the marking addition flag in the data in the packet is set to ON (step S706: Yes), the marking addition unit 214 that has passed the packet adds data indicating the presence or absence of marking to the packet header (step S706). S707), marking is added in the protocol header (step S708). When the marking addition flag in the data in the packet is set to OFF (step S706: No), the marking addition unit 214 adds data indicating the presence / absence of marking to the packet header (step S709), while the protocol is added. No marking is added in the header (step S710).

  Thereafter, the marking adding unit 214 transmits the packet to the base station 100b via the exchange side interface 216 (step S711). The above operation is repeatedly executed until transmission of all the frame data read from the content file is completed (step S712: Yes), and transmission of the content file is completed (step S713: Yes).

  According to this aspect, the marking addition mode is changed according to the marking flag embedded in the content file in advance. For example, in a moving image content file, a scene having relatively high importance information such as a telop is preliminarily embedded with a marking flag so as to reliably reach the UE 300.

  As described above, according to the series of operations described above, in a handover between base stations 100 having different communication methods, the handover destination base station 100b calculates a communication rate usable after the handover and calculates the handover source base station 100a. Notify This makes it possible to notify the data server 200 that provides the service from the handover source base station 100a of the communication rate that can be used after the handover.

  The data server 200 compares the communication rate available after the notified handover with the service rate. When the service rate exceeds the communication rate that can be used after the handover, the marking of the service data is started depending on the degree to which the service rate exceeds the communication rate.

  When the handover destination base station 100b receives service data with marking added from the data server 200 after handover, the base station 100b transmits a packet with marking or marking ON data to the UE 300. On the other hand, a packet without marking or with marking OFF data added is discarded without being transmitted.

  For this reason, only a part of the service data generated in the data server 200 can be finally set to be transmitted to the UE 300, and the capacity of the service data can be reduced. Thereby, the service rate required for transmission of service data can be reduced. Therefore, even when the communication rate after the handover is lower than that before the handover, it is possible to maintain the transmission of the appropriate service data and continue the service of a certain quality or higher. By appropriately changing the marking addition mode, it is possible to determine data to be discarded without being transmitted to the UE 300, and it is possible to prevent data having high importance from being discarded.

  Further, the base station 100b may be configured to temporarily store data in the radio side buffer 118 and then transmit the data to the UE 300 according to the communication rate. At this time, if the wireless-side buffer 118 is low in occupancy and has a free space, it is difficult to cause a communication delay even if data is temporarily stored. Therefore, the service data is transmitted after temporarily storing the data. With such a configuration, it is possible to appropriately transmit service data according to the communication rate, and it is possible to prevent data without marking from being discarded.

  On the other hand, if the wireless-side buffer 118 has a high occupancy and there is no free space, a communication delay occurs due to temporary storage of data. Therefore, priority is given to service continuation and data without marking is discarded. It is preferable to do.

  In the above description, the case where the communication rate available at the time of handover of the UE 300 changes is described as an example, but when the communication rate available to the UE 300 changes due to some other factor, The above-described marking process and accompanying transmission data selection may be performed. Even when used in such a case, it is advantageous in that it is possible to maintain transmission of appropriate data to the UE 300.

  In the above description, the data server 200 is described as an example of the service data provider for the UE 300, but other configurations may be employed. For example, at the time of communication between the mobile terminals UE300, when performing data communication from one UE300 to the other UE300, a setting for performing the marking addition process described above may be employed.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and mobile communication involving such changes. A system, a communication method, a base station, a server, and the like are also included in the technical scope of the present invention.

100 base station,
101 CPU,
102 memory,
103 bus switch,
104 digital signal processor (DSP),
105 (switch side) interface chip,
106 (wireless side) interface chip,
107 buffer memory,
111 call control unit,
112 Switch side protocol termination,
113 marking processing section,
114 Radio side protocol terminator,
115 Switch side interface,
116 wireless side interface,
117 network buffer,
118 Radio side buffer,
200 data server,
201 CPU,
202 memory,
203 bus switch,
204 Digital signal processor (DSP),
205 hard disk,
206 interface chip,
207 buffer memory,
211 Call control unit,
212 service data generation unit,
213 Switch side protocol generator,
214 Marking addition part,
215 data storage,
216 Switch side interface,
217 network buffer,
300 Mobile terminal (UE).

Claims (6)

A wireless communication system comprising a base station capable of communicating with a mobile terminal and a server provided above the base station,
The base station comprises notification means for notifying the server of a communication rate available at the base station,
The server includes marking means for marking predetermined data in the service data according to a difference between a service rate of service data to be transmitted to the mobile terminal and the notified communication rate.
The mobile communication system, wherein the base station transmits the service data transmitted from the server to the mobile terminal according to the presence or absence of marking for the service data. The base station further includes a buffer for temporarily storing data to be transmitted to the mobile terminal,
2. The base station according to claim 1, wherein the service data transmitted from the server is transmitted to the mobile terminal in accordance with the presence / absence of marking for the service data according to a free space of the buffer capacity. The mobile communication system according to 1.   2. The marking unit according to claim 1, wherein the marking unit performs the marking based on determination of whether the service data is data that prioritizes real-time property or data that prioritizes data reachability. Or the mobile communication system according to 2; A communication method in a wireless communication system comprising a base station capable of communicating with a mobile terminal and a server provided above the base station,
A notification step of notifying a communication rate available at the base station from the base station to the server;
A marking step of marking predetermined data in the service data according to a difference between a service rate of service data transmitted from the server to the mobile terminal and the notified communication rate;
A communication method comprising: a transmission step of transmitting the service data transmitted from the server to the base station from the base station to the mobile terminal according to the presence or absence of marking on the service data. In a mobile communication system, a base station that transmits data received from a server to a mobile terminal,
A notification means for notifying the server of a communication rate available in the base station;
Transmitting means for transmitting service data received from the server and transmitted to the mobile terminal to the mobile terminal according to the presence or absence of marking given to the service data according to the communication rate. A base station characterized by that. In a mobile communication system, a server that transmits service data to a mobile terminal via a subordinate base station,
In accordance with a difference between a service rate of service data transmitted to the mobile terminal and a communication rate that the base station can use for communication with the mobile terminal, predetermined data in the service data is transmitted to the mobile terminal. A server comprising marking means for marking for transmission.

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